diff --git a/include/gmssl/sm2_z256.h b/include/gmssl/sm2_z256.h
index 6789dcf7..c038c26e 100644
--- a/include/gmssl/sm2_z256.h
+++ b/include/gmssl/sm2_z256.h
@@ -40,7 +40,7 @@ void sm2_z256_rshift(sm2_z256_t r, const sm2_z256_t a, unsigned int nbits);
 uint64_t sm2_z256_add(sm2_z256_t r, const sm2_z256_t a, const sm2_z256_t b);
 uint64_t sm2_z256_sub(sm2_z256_t r, const sm2_z256_t a, const sm2_z256_t b);
 void sm2_z256_mul(sm2_z512_t r, const sm2_z256_t a, const sm2_z256_t b);
-uint64_t sm2_z256_get_booth(const sm2_z256_t a, unsigned int window_size, int i);
+int  sm2_z256_get_booth(const sm2_z256_t a, unsigned int window_size, int i);
 void sm2_z256_from_hex(sm2_z256_t r, const char *hex);
 int  sm2_z256_equ_hex(const sm2_z256_t a, const char *hex);
 int  sm2_z256_print(FILE *fp, int ind, int fmt, const char *label, const sm2_z256_t a);
diff --git a/src/sm2_z256.c b/src/sm2_z256.c
index a7a182fe..10d0c055 100644
--- a/src/sm2_z256.c
+++ b/src/sm2_z256.c
@@ -331,7 +331,7 @@ static uint64_t sm2_z512_add(sm2_z512_t r, const sm2_z512_t a, const sm2_z512_t
 	return c;
 }
 
-uint64_t sm2_z256_get_booth(const sm2_z256_t a, unsigned int window_size, int i)
+int sm2_z256_get_booth(const sm2_z256_t a, unsigned int window_size, int i)
 {
 	uint64_t mask = (1 << window_size) - 1;
 	uint64_t wbits;
@@ -346,10 +346,10 @@ uint64_t sm2_z256_get_booth(const sm2_z256_t a, unsigned int window_size, int i)
 	j = j % 64;
 
 	wbits = a[n] >> j;
-	if ((64 - j) < (window_size + 1) && n < 3) {
+	if ((64 - j) < (int)(window_size + 1) && n < 3) {
 		wbits |= a[n + 1] << (64 - j);
 	}
-	return (wbits & mask) - ((wbits >> 1) & mask);
+	return (int)(wbits & mask) - (int)((wbits >> 1) & mask);
 }
 
 void sm2_z256_from_hex(sm2_z256_t r, const char *hex)
@@ -1459,11 +1459,8 @@ void sm2_z256_point_mul(SM2_Z256_POINT *R, const sm2_z256_t k, const SM2_Z256_PO
 
 int sm2_z256_point_print(FILE *fp, int fmt, int ind, const char *label, const SM2_Z256_POINT *P)
 {
-	sm2_z256_t x;
-	sm2_z256_t y;
 	uint8_t affine[64];
 
-
 	if (sm2_z256_point_is_at_infinity(P) == 1) {
 		format_print(fp, fmt, ind, "%s: point_at_infinity\n", label);
 	} else {
diff --git a/src/sm9_z256.c b/src/sm9_z256.c
index 70ccf344..9777c9ac 100644
--- a/src/sm9_z256.c
+++ b/src/sm9_z256.c
@@ -385,7 +385,7 @@ void sm9_z256_to_hex(const sm9_z256_t r, char hex[64])
 {
 	int i;
 	for (i = 3; i >= 0; i--) {
-		(void)sprintf(hex + 16*(3-i), "%016llx", r[i]);
+		(void)sprintf(hex + 16*(3-i), "%016lx", r[i]);
 	}
 }